This invention relates to drill bits, specifically drill bit assemblies for use in oil, gas and geothermal drilling. Often drill bits are subjected to harsh conditions when drilling below the earth's surface. Replacing damaged drill bits in the field is often costly and time consuming since the entire downhole tool string must typically be removed from the borehole before the drill bit can be reached. Bit balling in soft formations and bit whirl in hard formations may reduce penetration rates and may result in damage to the drill bit. Further, loading too much weight on the drill bit when drilling through a hard formation may exceed the bit's capabilities and also result in damage. Too often unexpected hard formations are encountered suddenly and damage to the drill bit occurs before the weight on the drill bit may be adjusted. In addition, factors such as formation hardness, bit load and bit composition may impact the rate of penetration (ROP) of the drill bit into the formation. The prior art discloses shear bits with steel or carbide matrix blades.
U.S. Pat. No. 5,947,215, which is herein incorporated by reference for all that it contains, discloses a rock drill bit for percussive drilling including a steel body in which six gauge buttons and a single front button are mounted. The gauge buttons are arranged symmetrically and equally spaced about a central axis of the bit. The front button is arranged along the central axis. The front button is of larger diameter than the gauge buttons are diamond-enhanced, and the front button may be diamond enhanced.
U.S. Pat. No. 7,070,011 to Sherwood, Jr. et al., which is herein incorporated by reference for all that it contains, discloses a steel body rotary drag bit for drilling a subterranean formation that includes a plurality of support elements affixed to the bit body, each forming at least a portion of a cutting element pocket.
U.S. Pat. No. 5,333,699 to Thigpen et al., which is herein incorporated by reference for all that it contains, discloses a drill bit having polycrystalline diamond compact cutter with spherical first end opposite cutting end.